1. Field of the Invention
This invention relates generally to tamper evident end closures for containers, and more particularly, to an end closure for a container for retaining a comestible product.
2. Description of the Prior Art
Containers of the type with which the present invention is concerned include end closures which maintain the container in a sealed condition after packaging and provide a non-resealable top to indicate tampering with the container if the end closure is moved.
One type of previously available tamper evident container included a rotatable cap portion formed with a knife and a weakened annular portion in the end of the container. The knife requires separate manual engagement with a weakened groove in the end of the container. The cap is then rotated, causing the knife to completely sever the weakened portion of the end portion, opening the container. This conventional arrangement results in a cap which is easily detachable from the container and thus inconvenient to use. Furthermore, means are not provided for maintaining alignment of the knife blade with the weakened annular portion during movement of the knife to sever said portion. This type of construction is disclosed in U.S. Pat. No. 378,349.
It is also known to provide a sealed container with a thin member or weakened membrane functioning as the seal. A helically threaded nozzle portion having a plurality of depending knives is threaded about the outer lip of the container, so that the blades are gradually brought into contact with the thin member. As the nozzle is threaded about the throat of the container, the blades gradually pierce the membrane and open the container. This structure does not provide a hinged cap when the cutting operating is complete, but merely secures the nozzle to the container and insures communication of the contents therein with the end of the nozzle. Furthermore, once the nozzle is removed, it may be easily displaced from the container. Such a container is shown generally in U.S. Pat. No. 3,402,855.
U.S. Pat. No. 4,125,203 discloses a twist top for use with pull tab type beverage containers wherein the outer rotatable lid is attached to one end of the tab so that rotation of the lid pulls the tab away from the aperture of the container and also aligns an aperture in the lid with the aperture of the container to allow access to the beverage contained therein. This patent does not disclose the use of a rotatable outer cap with an intergral knife blade to sever an annular band in the body portion of a container and provide a hinged lid for the container.
U.S. Pat. No. 4,567,995 in the name of the same inventor as the inventor herein discloses an end closure for a container having a closed end with a cover rotatable thereabout. The closed end has a raised portion which is engaged by a knife blade integral with the cover. As the cover is rotated, the blade severs the raised portion, revealing an aperture providing access into the container. In this device, the closed end is not completely opened, nor is it hinged.
U.S. Pat. No. 4,598,837 also issued to the same inventor as the inventor herein discloses a tamper evident element in a container wherein rotation of an outer rotatable element causes an integral knife blade to sever and detach said element from the container, thus evidencing tampering when the cover is moved. This type of container is suitable for retaining food products in which small amounts are used at a time, but is not suitable for retaining food products such as frozen juices which, when the container is opened, are intended to be totally discharged from the container promptly or after a short storage period only.
Thus, it is desired to provide a temper evident container which can be used for comestibles which are intended to be discharged in bulk from the container. It also is desired to provide a tamper evident container in which the rotating overcap knife blade which opens the container by rotation of an outer cap is provided with structure to automatically engage a weakened wall portion of the container and maintain alignment of the blade with said wall portion. The closure of the present invention includes an overcap rotatably secured to the closed end of a container and is provided with an integral knife blade. Twisting the overcap relative to the container causes the knife to engage and sever the container sidewall to create a hinged lid and expose the contents for removal. Once the overcap has been rotated to any significant extent, tampering of the container is evidenced.